New Delhi, May 8 (Inditop.com) After the success of Marvel superhero “Iron Man” on the big screen, shooting for the second instalment was tiresome, confesses Robert Downey Jr. who reprises his role as the billionaire inventor Tony Stark and Iron Man in the highly-anticipated sequel.

“‘Iron Man’ emerged as a winner because Iron Man is different from the usual super heroes and he feels like a real person. The character of Tony Stark is glamorous, successful and virile, yet he has a very vulnerable side to him,” Downey Jr. said during an e-mail interaction with the media from Los Angeles.

“(So) the confidence was higher and the story is actually significantly more complex and subtle. We felt more responsible to spend more time and we had broadened our cast and horizons (for this one). It was a really, really, really trying process to get this done to the best of our ability,” added the actor, who was last seen in Guy Ritchie’s big-screen adaptation of “Sherlock Holmes”.

Distributed by Paramount Pictures, “Iron Man 2” has been directed by Jon Favreau. It released Friday in India and the US.

Also starring in the action-adventure sci-fi thriller are Gwyneth Paltrow, Don Cheadle, Scarlett Johansson, Mickey Rourke and Samuel L. Jackson.

Throwing light on his character’s journey from the first movie to the second, Downey Jr. said: “In the first film Tony was in this kind of nether-world, somebody who needed to be put in check. By the time ‘Iron Man 2’ starts you’re essentially seeing Tony’s persona, and he’s showing that persona to everything and everyone around him because he doesn’t want them to know that anything has changed.”

“But a lot has changed, and he’s really in quite a desperate way. The hero’s journey is really what he’s not telling people, not what he’s doing with or without a suit on,” he added.

So what do the audiences get to see in ‘Iron Man 2’?

“Tony has noticed that the shelf life on his battery is nearing its expiration date. So he’s been spending a lot of time working on a renewable energy source,” said the 45-year-old.

“We also left off on the first film with Tony and the military having a somewhat uneasy relationship though when he comes in and does something right they back him up. And there’s also been some climbing tension between Tony and his good friend Lt. Colonel James ‘Rhodey’ Rhodes,” he added.

Downey Jr.’s future projects include “Due Date” and multiple superhero movie “The Avengers” where he reprises his role as Tony Stark/Iron Man. An “Iron Man 3” movie is also in the offing.